This application is based on and claims priority under 35 U.S.C. xc2xa7119 with respect to Japanese Patent Application No. 2000-258976 filed on Aug. 29, 2000, the entire content of which is incorporated herein by reference.
The present invention is generally directed to vehicle bumpers. More particularly, the present invention pertains to a bumper apparatus provided on at least one of the front and rear ends of a vehicle.
A known bumper apparatus for absorbing an impact to a passenger and a vehicle body incurred in a vehicle collision is disclosed in a Japanese Patent Application Publication published on Jul. 20, 1993 as Toku-Kai-Hei 5(1993)-178144. This known bumper apparatus is disposed on side members on both sides near either the front or rear end of the vehicle body, and the opposite ends thereof are attached to the side members. The bumper reinforcement extends in the vehicle width-wise direction of the vehicle body and has a uniform cross-section in the span thereof. An absorber and a bumper cover are overlaid on the outer surface of the bumper reinforcement in a direction applied with an impact load incurred during the vehicle collision.
The bumper reinforcement, as a main member of the bumper apparatus, is formed by a hollow member that is generally defined by outer and inner walls, top and bottom walls, and a center wall between the top and bottom walls. The bumper reinforcement absorbs an impact incurred upon vehicle collision by plastic deformation of each portion such as the middle or both ends thereof, thereby preventing damage to the vehicle body.
A bumper reinforcement including a more effective mechanism for preventing damage to the vehicle body upon vehicle collision is proposed in a Japanese Patent Application Publication published on Aug. 2, 1994 as Toku-Kai-Hei 6(1994)-211090. This bumper reinforcement also has a uniform cross-section across the span thereof, but has attachments to the side members that are weakened by providing a hole thereon.
A bumper reinforcement having the uniform cross-section is unsuitable for a bumper apparatus that is to be fitted in a complex curve of the vehicle body. A bumper reinforcement with such uniform cross-section also cannot have a sufficient thickness of the absorber disposed between the bumper reinforcement and the bumper cover.
Accordingly, the known bumper apparatus is unable to absorb the impact of a vehicle collision by the bumper reinforcement alone, and so the bumper apparatus needs to have additional members to reinforce the side members. Therefore the number of parts forming the bumper apparatus is increased, and the structure of the vehicle body including the side members and the additional members becomes complicated.
Accordingly, a need exists for a bumper apparatus having an improved ability to absorb the impact resulting from a vehicle collision.
In accordance with one aspect of the invention, a bumper apparatus for a vehicle includes a first reinforcement, and a second reinforcement extending in the vehicle width-wise direction. The second reinforcement has a first outer wall at a side remote relative to the vehicle body, an inner wall at a near side relative to the vehicle body, and a first top wall and a first bottom wall connecting the first outer wall with the inner wall. The second reinforcement further includes two end portions and an intermediate portion located between the end portions, with both end portions being fixed to the vehicle body via the first reinforcement. At least a portion of the inner wall disposed in the intermediate portion being caved in to gradually approach toward the first outer wall from the both end portions.
The bumper apparatus can also be provided with one or more side members disposed between the second reinforcement and the vehicle body. The first reinforcement can be defined by one or more hollow members having a second top wall and a second bottom wall which are welded to the first top wall and the first bottom wall of the second reinforcement, respectively. In addition, the first reinforcement can be configured to have a center wall disposed between the second top wall and the second bottom wall, and a second outer wall positioned to oppose and contact the inner wall of the second reinforcement.
The inner wall of the second reinforcement can be provided with a first groove whose cross section is U-shaped at the intermediate portion, with the first groove being gradually deepened from the side of the one of the end portions to the center of the intermediate portion. Also, the first outer wall can be provided with a second groove whose cross section is U-shaped at each of the end portions, with the second groove being gradually deepened from the center of the intermediate portion toward the outside in the vehicle width-wise direction.
The bumper apparatus of the present invention provided with the bumper reinforcement is advantageous in that its thickness in the vehicle longitudinal direction at both ends is larger than in the center portion thereof. In addition, the inner wall of the intermediate portion is strengthened by having the portion that is caved in gradually toward the outer wall. Therefore the bumper apparatus can obtain a sufficient capacity to resist an impact load, thereby increasing its capacity to absorb the energy generated by a vehicle collision.
According to another aspect of the invention, a bumper apparatus for a vehicle includes a first reinforcement and a second reinforcement connected to the first reinforcement and extending in a width-wise direction of the vehicle. The second reinforcement includes an outer wall at a side remote from the vehicle body, an inner wall at a side near the vehicle body, and a first top wall and a first bottom wall connecting the first outer wall with the inner wall. The second reinforcement further includes an intermediate portion located between two end portions with respect to the width-wise direction of the vehicle, with each of the end portions being fixed to the vehicle body via the first reinforcement. The inner wall is provided with a U-shaped groove having a depth that varies along the width-wise direction of the second reinforcement.